1. Field of the Invention
The present invention relates to processors for chipping and shredding vegetation and, in particular, to machines having cutters mounted on a rotor.
2. Description of Related Art
Known chippers have employed a relatively heavy, steel disk mounted in a cylindrical housing. The disk has slots where cutting blades are mounted. The disk housing has a hopper for feeding branches and limbs through the side of a housing and into the spinning cutter blades. A cutter bed bar can be mounted in the cylindrical housing to subjacently support the lower edge of the hopper opening and provide a firm platform to hold the material against the action of the cutter blades. These known chippers can be driven by a gasoline engine or by a drive shaft adapted to be connected to the drive train of a tractor or other machine.
In some embodiments, the rating of the chipper is determined by the angular momentum stored in the chipper rotor. Such designs anticipate spinning a relatively heavy rotor at a high speed. Consequently, wood fed into the chipper blades would tend to slow the rotor but not unacceptably so if the wood is of a rated size.
An advantage with this type of design is the fact that the motor or drive shaft spinning the chipper rotor need not have the horsepower needed to supply all of the power required when the chipping is actually occurring. Instead, the motor can store kinetic energy in the rotor using a flywheel effect, so that energy can be withdrawn quickly during chipping without excessively loading the motor.
A conventional shredder can employ a plurality of coaxial disks mounted inside a cylindrical housing. Swinging bars or flails can be mounted between the coaxial disks to articulate and assist in the shredding process. While material to be chipped is brought to the side of a rotating disk, material to be shred conventionally is fed radially into the spaces between the rotating disks.
Chippers and shredders are often used by landscapers, farmers, foresters or others who must reduce various types of materials. For this reason, combined chipper/shredders have been designed. Such combined chipper/shredders have employed two hoppers, one to feed shreddable material radially between coaxial disks and another hopper to feed chippable material to the side of an outer disk carrying chipper blades.
A combined chipper/shredder is disclosed in U.S. patent application 08/000,621, filed Jan. 5, 1993 and entitled Processor for Chipping and Shredding Vegetation. The disclosure of that application is incorporated herein by reference. This processor was designed to have a close fit between the processor housing and the rotor carrying the cutter blades. The close fit ensured that the processor worked efficiently and material fed into the hopper did not bypass the rotor. Were a loose fit employed, twigs could be thrown centrifugally into the space between the housing and the rotor where they could either bypass the rotor or accumulate to cause binding of the rotor. While keeping a small rotor to housing spacing is workable, using looser tolerances are preferable.
Also in this same machine, the illustrated flails are mounted in four quadrants between four equiangularly spaced vanes. The flails can recoil upon encountering heavy material or striking debris built up on the inside of the housing. A recoiling flail can hit a neighboring vane, causing wear and potential damage. In addition, the flails can swing backwards when accelerating at start up or forwards when decelerating at shut off. Such swinging can also cause the flails to swing and hit the vanes.
U.S. Pat. No. 3,276,700 shows a wood chipper employing a rotary disk with angularly spaced knives and passageways. Material is fed to one side of the disk and chips pass through the other side while air is continuously circulated throughout the housing.
U.S. Pat. No. 3,756,517 shows a forage blower with a recutter. Material is transferred from the cutter to the impeller in the direction of rotation of the impeller. Therefore, the exit velocity of the material has a significant component towards the discharge opening. This assembly includes a perforated cylindrical screen or cage. Material passing through the cage is thrown into impeller paddles which sweep the recut materials into an outlet. See also U.S. Pat. Nos. 2,361,278; 3,276,700; 3,917,176; 4,951,882.